1. Technical Field
The present invention relates to a common mode filter with a electrostatic discharge (ESD) protection pattern built therein, and more particularly, to a common mode filter with an ESD protection pattern built therein, in which an external electrode terminal of the common mode filter is divided into a first external electrode terminal and a second external electrode terminal, and the ESD protection pattern is built therebetween so that a function of the common mode filter and a static eliminating function are integrated into a single electronic component to be implemented, and therefore a mounting area is reduced at the time of application of an SET product.
2. Description of the Related Art
In recent years, electronic apparatuses such as mobile phones, home appliances, personal computers (PC), personal digital assistants (PDA), liquid crystal displays (LCD), navigations, and the like have been gradually digitalized with faster speeds. Since the electronic apparatuses are sensitive to external stimulation, there occurs a case in which the circuits are damaged or signals are distorted when slightly abnormal voltage and high frequency noise flow into an internal circuit of the electronic apparatus from the outside.
As the causes of the abnormal voltage and the noise, a switching voltage generated in the circuit, a power source noise included in a power supply voltage, unnecessary electromagnetic signals or noises, or the like may be given, and as a means for preventing the abnormal voltage and the high frequency noise from flowing into the circuit, a filter may be used.
In a general differential signal transmission system, together with a common mode noise filter for removing common mode noises, a passive component such as a diode, a varistor, or the like has to be separately used to prevent electro static discharge (Hereinafter, referred to as “ESD”) that may occur in an input/output terminal.
In this manner, when the separate passive component is used in the input/output terminal so as to correspond to the ESD, a mounting area and manufacturing costs may be increased, and distortion of signals may occur.
For example, in order to suppress the ESD using the varistor, internal electronic components of the electronic apparatus are protected in such a manner that an end of the varistor is connected to the input/output terminal and the other end thereof is connected to a ground terminal.
However, the varistor acts as a capacitor in a normal operation state of the electronic apparatus to which a transient voltage is not applied. Since the capacitor has a capacitance value that changes at a high frequency, there occurs a problem such as occurrence of signal distortion, or the like when an element of the varistor is used in a data input/output terminal at a high frequency or a high speed, or the like.
Meanwhile, a protection element such as the common mode noise filter, the varistor, or the like may be formed in a rectangular parallelepiped shape, and an internal electrode may be provided inside the protection element, and an external electrode that is connected with the internal electrode may be provided outside the protection element.
In addition, a ground electrode may be provided inside the protection element, and another external electrode that is connected with the ground electrode may be provided outside the protection element.
However, the external electrode that is connected with the internal electrode is provided on one side and the other side of the element, and the external electrode that is connected with the ground electrode is provided on a side surface of the element in a direction that intersects with the one side and the other side of the element.
That is, the external electrode that is connected with the internal electrode and the external electrode that is connected with the ground electrode are formed respectively on mutually different side surfaces.
Accordingly, the external electrode is formed on all side surfaces of the element. In addition, in order to mount the element on a printed circuit board, a space for connecting the external electrode and a wiring printed on the printed circuit board is required.
However, in a structure of the element according to the related art in which the external electrode is provided on all side surfaces of the element, there is a limitation in securing a spare space of the printed circuit board, and therefore design of the printed circuit board is difficult.